In general, tetracarboxylic dianhydrides are useful as raw materials for producing polyimide resins, as epoxy curing agents, and as the like. Of the tetracarboxylic dianhydrides, aromatic tetracarboxylic dianhydrides such as pyromellitic dianhydride have been mainly used as raw materials for polyimide resins used in the field of electronic devices or the like. Then, as a polyimide obtained by using such an aromatic tetracarboxylic dianhydride, for example, a polyimide (trade name: “Kapton”) has been conventionally widely known which is marketed by DU PONT-TORAY CO., LTD. and which is a material necessary for cutting-edge industries for aerospace and aviation applications and the like. Conventional polyimides obtained by using aromatic tetracarboxylic dianhydrides have excellent physical properties in terms of heat resistance; however, such polyimides are colored (yellow to brown), and cannot be used in the optical and other applications where transparency is necessary. For this reason, to produce a polyimide usable in the optical or other applications, tetracarboxylic dianhydrides which can be preferably used as monomers for producing polyimides have been researched.
Conventionally, various types of compounds have been disclosed as tetracarboxylic dianhydrides for producing polyimides having high light transmittance. For example, Japanese Unexamined Patent Application Publication No. Sho 55-36406 (PTL 1) discloses 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, and Japanese Unexamined Patent Application Publication No. Sho 63-57589 (PTL 2) discloses bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic dianhydride. Meanwhile, Japanese Unexamined Patent Application Publication No. Hei 7-304868 (PTL 3) discloses bicyclo[2.2.2]octanetetracarboxylic dianhydride as a raw material for a polyimide resin. Moreover, Japanese Unexamined Patent Application Publication No. 2001-2670 (PTL 4) and Japanese Unexamined Patent Application Publication No. 2002-255955 (PTL 5) disclose 1,2-bis(4′-oxa-3′,5′-dioxotricyclo[5.2.1.02,6]decan-8′-yloxy)ethane. Moreover, Japanese Unexamined Patent Application Publication No. Hei 10-310640(PTL 6) discloses bicyclo[2.2.1]heptane-2,3,5-tricarboxyl-5-acetic 2,3:5,5-acid dianhydride. However, when a polyimide is produced by using a conventional tetracarboxylic dianhydride described in any of PTLs 1 to 6, the obtained polyimide has a sufficient light transmittance, but the heat resistance of the polyimide is not sufficient. Hence, it is difficult to practically use such a polyimide in the optical or other applications.
Meanwhile, studies on tetracarboxylic dianhydrides have further conducted to solve the above-described problems recently, and some tetracarboxylic dianhydrides have been reported from which polyimides sufficiently practical for use in the optical applications can be produced. For example, International Publication No. WO2011/099518 (PTL 7) discloses a norbornane-2-spiro-α-cycloalkanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylic dianhydride having a specific structure, and reports that a polyimide having a sufficiently high light transmittance and a sufficiently high heat resistance can be produced by using such a tetracarboxylic dianhydride.
Under such circumstances, the development of a novel tetracarboxylic dianhydride which has characteristics (light transmittance, heat resistance, and the like) equal to or superior to those of the above-described tetracarboxylic dianhydride described in PTL 7, and which can be produced more easily has been demanded in the field of tetracarboxylic dianhydride.